New Zealand: Spraying copper is key to quality avocados

After visiting large orchards in Australia where copper applications are a key feature of fruit quality control, Far North avocado grower Ross Mutton is convinced the spray helps ensure avocados get in top condition. Copper spraying and the removal of dead wood and plant material from around trees are essential procedures in avocado orchards.

Mutton produces about 30,000 trays of avocados annually from 16 canopy hectares of trees on 10 hectares at Paparore, about 15km north of Kaitaia, and 9.78 hectares at Houhora. He's a member of Avoco's Grower Relations Committee and was among a group of growers who travelled to Western Australia and Queensland last year to learn about methods used on three family-owned orchards, each producing more than a million trays of avocados most years.

Copper spraying is considered the most effective way to prevent fungal rot, which starts in the orchard through infection of fruit, but usually doesn't emerge until post-harvest.

New Zealand's wet climate and the distance the fruit travels to market means Kiwi avocado growers must spray to preserve fruit quality. Mr Mutton said they can't afford to be complacent or avoid spraying because of the financial costs, which are around $800 a canopy hectare.

"Smaller growers in New Zealand might have a copper bill of up to $4000, but Australian growers spend a whole lot more because they are much closer to the problems when they arise. In reality, we have even more reasons to spray than the Australians because our fruit has further to travel, putting it at greater risk of post-harvest ripening disorders."

According to, Avoco -New Zealand's largest avocado export supply group- advises growers to get rid of dead wood and mummified fruit through mulching and pruning to let light in. This, together with wind protection, trying to increase fruit calcium levels and soft fruit handling are collectively as important as copper sprays.

Avoco is expected to export about 1.3 million trays of avocados this season.

Publication date: 2/16/2018

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